1. Field of the Disclosure
The present disclosure relates to a liquid crystal display (LCD) device, and particularly, to an LCD device including an inspection circuit, the device having a structure such as a column inversion type or a Z-inversion type where a single data line can be shared by two neighboring pixels, and an inspection method thereof.
2. Background of the Disclosure
With development of information electronic devices including various types of portable devices such as a mobile phone and a notebook computer, an HDTV, etc. for implementing images of high resolution and high quality, demands for flat panel display devices applied thereto increase. Such flat panel display devices include LCD (Liquid Crystal Display), PDP (Plasma Display Panel), FED (Field Emission Display), OLED (Organic Light Emitting Diodes), etc. However, among such flat panel display devices, the LCD devices are spotlighted because of characteristics of massive production, easy driving, high quality, and a large screen.
An active matrix-type LCD device where a thin film transistor (TFT) is used as a switching device, is particularly suitable for displaying moving images.
Generally, the LCD device for displaying images has a column inversion structure, a line inversion structure and a dot inversion structure, so as to prevent degradation of liquid crystals and to enhance a picture quality. The dot inversion structure has a higher picture quality than the column inversion or the line inversion. However, the dot inversion structure has high power consumption and lowering of a pixel charging characteristic, because a data signal applied to each data line should be inversed per horizontal period. On the contrary, the column inversion structure has an advantage that a pixel charging characteristic is excellent because data signals of the same polarity are applied data lines for each horizontal period. However, the column inversion structure has a disadvantage that inferiority of vertical cross torque may occur because pixels on the same vertical line have the same polarity.
In order to solve such problems of the column inversion structure and the dot inversion structure, has been proposed an enhanced column inversion structure.
FIGS. 1A and 1B are views showing part of an LCD device having an enhanced column inversion structure in accordance with the conventional art.
As shown, the conventional LCD device having an enhanced column inversion structure includes a plurality of gate lines (GL1˜GL6) and data lines (DL1˜DL7) crossing each other, and a plurality of pixels (P11˜P22) formed at the crossing points. Pixels (P11,P21) arranged on the same horizontal line are connected to the same gate line (GL1), and pixels (P11,P12) arranged on the same vertical line are connected to different data lines (DL1,DL2).
The LCD device having such enhanced column inversion structure operates in the same manner as an LCD device having a general column inversion structure, by alternately applying data signals of a positive polarity (+) and a negative polarity (−) to neighboring data lines in a normal mode, and by inversing the polarities of the data signals per frame. However, the enhanced column structure has the same effect as the dot inversion structure because the upper and lower pixels (P11, P22) arranged to cross each other are connected to a single data line (DL1).
Accordingly, the enhanced column inversion structure can implement the same picture quality as the dot inversion structure, with obtaining a sufficient charging time for each pixel.
However, the LCD device having such column inversion structure has a difficulty in inspecting whether each pixel is normally driven. For instance, as shown in FIG. 1A, high gate driving signals (VGH) are applied to all of the gate lines (GL1˜GL6), so as to inspect whether R pixels are normally driven. A gate driving unit (not shown) for supplying signals to the gate lines (GL1˜GL6) has a GIP (Gate In Panel) structure. According to the GIP structure, the gate driving unit is mounted on an LC panel together with pixels through the same processes. Such gate driving unit has a structure where a plurality of shift registers sequentially operate, and is driven by sequentially or simultaneously applying high gate driving signals (VGH) to the respective gate lines (GL1˜GL6).
If the high gate signals (VGH) are simultaneously applied to all of the gate lines (GL1˜GL6), transistors (T) of all pixels are turned-on. And, full-gray data signals are applied to data lines (DL1, DL4, DL7) connected to R pixels, among all of the data lines (DL1˜DL7). The data driving unit is not mounted in an LC panel, but is attached to the LC panel in the form of a separate integrated chip (IC). And, the data driving unit may individually apply signals to the data lines (DL1˜DL7). Accordingly, for inspection of specific pixels, data signals are applied only to data lines connected to the specific pixels. However, even if data signals are applied only to the data lines (DL1, DL4, DL7) connected to the R pixels, color mixture may occur because the R pixels are together driven with B pixels also connected to the data lines (DL1, DL4, DL7). This may cause a pattern with respect to a single color not to be implemented.
Further, if full-gray data signals are applied to data lines (DL2, D5) connected to other R pixels or G pixels for inspection of said other R pixels or G pixels, said other R pixels and G pixels are together driven to cause color mixture. This may cause a difficulty in precisely inspecting whether each pixel is normally driven or not.